The phone hacking scandal would not have come to light without unofficial meetings between police officers and the press, the journalist responsible for breaking the story has said.

Nick Davies, who writes for the Guardian, told the Leveson Inquiry the police should not be prevented from speaking to journalists without authorisation from press officers, and that losing unauthorised contact would lead into “dangerous territory”.

He added: “Without unauthorised contact between the press and police the Met police would have been allowed to carry on misleading press, parliament and the public about the phone hacking scandal.”

Davies, appearing before the inquiry for the second time, said such relationships only become problematic if they prevent investigations, such as the original 2006 investigation into phone hacking, from being carried out correctly.

He said: “Something went catastrophically wrong in that inquiry and its subsequent public statements. If part of that failure was to do with cosy relationships which existed between the tops of those two organisations you can see how the relationship can go wrong.”

The journalist told Lord Justice Leveson that 90 percent of the work he does is off the record, meaning he will use the information in stories but will not attribute it to specific individuals. He said material provided from press officers can be inaccurate and “out of step” with the needs of the public, as they are employed to protect the interests of the organisation.

Davies told the inquiry last November he had developed a series of stories on the phone hacking revelations, published in the Guardian, from a briefing from Scotland Yard and consulting with human sources.

Also appearing before the inquiry for a second time was Chris Jefferies, the former landlord of murder victim Joanna Yeates. He gave evidence detailing his experience with the police and press following his arrest for the murder in 2010, of which he was later cleared.

The former teacher discussed evidence given by Daily Mirror editor Richard Wallace, who said journalists from the paper were told in an unofficial briefing that Avon and Somerset police “were confident Mr Jefferies was their man.”

Lord Justice Leveson said he had received a letter from the police force challenging Wallace’s statements “in a number of respects”.

Jefferies said he believed police took a long time to lift his bail in order to suggest he had been arrested on the basis of stronger evidence that was the case. He was cleared as a suspect in March 2011 even though Vincent Tabak had been charged two months earlier, after confessing to manslaughter. Tabak was subsequently convicted for Joanna Yeates’ murder.

Avon and Somerset police have denied leaking information to the press but admitted accidently disclosing Jefferies’s name to journalists. Jefferies told the inquiry information published in the Daily Mail the day before his arrest could only have come from his police statement. The paper reported Jefferies had heard Yeates leave the property with two other people, when in fact he had told police he could not identify the individuals, or whether one of them was his tenant.

He said it should be an imprisonable offence for police to disclose inappropriate information to journalists.